The production and use of acrylic acid (AA) has grown significantly in recent decades as the demand for polyacrylic acid-based superabsorbent polymers (SAPs) has grown. SAPs are used extensively for the manufacture of diapers, adult incontinence products, and feminine hygiene products, as well as in agricultural applications.
Currently, commercial acrylic acid is typically derived from propylene oxidation. Propylene is primarily a product of oil refining and its price and availability are closely tied to crude oil prices. Because of this, acrylic acid prices remain tied closely to the price of oil and its fluctuations.
Thus, there exists a need in the art for alternative methods to synthesize acrylic acid. At the same time, it would be preferred to produce acrylic acid from renewable resources. US patent application publications 2015/0183708 published Jul. 2, 2015 and 2014/0018574 filed Jan. 15, 2014 disclose the production of bio-based acrylic acid from poly-3-hydroxypropionate using a wide variety of biologically active materials.
Other references disclose producing acrylic acid from bPL (β-propiolactone) with inorganic catalysts. U.S. Pat. No. 3,176,042 disclosed a phosphoric acid catalyzed process for the production of acrylic acid from bPL. Due to corrosiveness of phosphoric acid and slow reaction rate this process is capital intensive. Additionally, water has to be fed to the reactor continuously to maintain the composition of phosphoric acid inside the reactor at the desired levels. This leads to the need to separate water from the produced acrylic acid resulting in additional equipment and operating costs.
U.S. Pat. No. 9,096,510 B2 teaches production of acrylic acid from bPL using a solid catalyst in at least partial gas phase conditions.
WO20133191 teaches production of acrylic acid from bPL in a two-step process: at first bPL is polymerized to produce poly-propiolactone and then acrylic acid is produced via thermolysis of poly-propiolactone. This process capital intensive and has high operating costs as highly exothermic polymerization reaction is followed by highly endothermic thermolysis reaction.
Thus, improved methods are sought to produce acrylic acid, especially high purity acrylic acid from non-hydrocarbon and preferably renewable sources.